790 results
Showing 461–480 · 0.18 seconds · RSS
-
Journal Article
An Improved Thermo-TDR Technique for Monitoring Soil Thermal Properties, Water Content, Bulk Density, and Porosity
The thermo-time domain reflectometry (thermo-TDR) technique is valuable for monitoring in situ soil water content (θ), thermal properties, bulk density (ρ), porosity (), and air-filled porosity () in the vadose zone. However, the previous thermo-TDR sensor has several weaknesses, including limited…
-
Journal Article
Evaluation of Parametric and Nonparametric Machine-Learning Techniques for Prediction of Saturated and Near-Saturated Hydraulic Conductivity
Parametric and nonparametric supervised machine learning techniques were used to estimate saturated and near-saturated hydraulic conductivities ( and , respectively) from easily measurable soil properties including the name of the pedological horizon (HOR), soil texture (sand, silt, and clay)…
-
Journal Article
Analogue Fracture Experiments and Analytical Modeling of Unsaturated Percolation Dynamics in Fracture Cascades
Infiltration and recharge dynamics in fractured aquifer systems often strongly deviate from diffuse Darcy–Buckingham type flows due to the existence of a complex gravity-driven flow component along fractures, fracture networks, and fault zones. The formation of preferential flow paths in the…
-
Journal Article
Simulation of Channelized Gas Flow Pattern in Heterogeneous Porous Media: A Feasibility Study of Continuum Simulation at Bench Scale
In remediation technologies, air or O gas is injected into a polluted aquifer to remove organic contaminants. A gas injection process is also applied in enhanced oil recovery and CO sequestration. The wide range of gas injection processes into porous media necessitates accurate gas flow modeling…
-
Journal Article
Scale Issues in Soil Hydrology
Soil hydrology is a key control for the functioning of the terrestrial environment. Many environmental issues that we need to tackle today are directly linked to soil water dynamics. This includes agricultural production and food security, nutrient cycling and carbon storage, prevention of soil…
-
Journal Article
How Critical Is the Assimilation Frequency of Water Content Measurements for Obtaining Soil Hydraulic Parameters with Data Assimilation?
Data assimilation (DA) is a promising alternative to infer soil hydraulic parameters from soil water dynamics data. Frequency of measurements and updates are important controls of DA efficiency; however, no strict guidance exists on determining the optimal frequency. In this study, DA was performed…
-
Journal Article
Measurement of Gas Diffusion Coefficient in Highly Permeable Porous Media
Gas diffusion is a fundamental transport process in porous media. However, to date, there is no method for experimentally estimating the gas diffusion coefficient of coarse porous media. A modified method is proposed here and was validated against sand media. The method was tested using particle…
-
Journal Article
A Pedotransfer Function for Field-Scale Saturated Hydraulic Conductivity of a Small Watershed
Classical experimental techniques to determine point values of saturated hydraulic conductivity () are complex and time consuming; therefore, the development of pedotransfer functions, PTFs, to derive from easily available soil properties is of great importance. However, PTFs have been generally…
-
Journal Article
Comparison of Soil-Freezing and Soil-Water Characteristic Curves of Two Canadian Soils
The drying–wetting and freezing–thawing cycles significantly influence the soil pore water in the vadose zone in permafrost and seasonally frozen regions. The soil-freezing characteristic curve (SFCC) describes the relationship between unfrozen water content and subzero temperature in a soil at…
-
Journal Article
Water Retention and Pore Size Distribution of a Biopolymeric-Amended Loam Soil
The pore size distribution (PSD) of biopolymeric-amended soils is rarely investigated due to difficulties in its quantification using classical methods. In this study, we analyzed the impact of biopolymeric soil amendments on the PSD of a dryland loamy soil based on its physical and biological…
-
Journal Article
Extension of the Cylindrical Root Model for Water Uptake to Non-Regular Root Distributions
The water flow toward a single root is efficiently solved in cylindrical coordinates using the matrix flux potential. The upscaling of single root fluxes to whole root systems is commonly based on the assumption of regularly distributed and parallel aligned roots. To provide more accurate solutions…
-
Journal Article
Combination of Magnetic Resonance Imaging and Neutron Computed Tomography for Three-Dimensional Rhizosphere Imaging
In situ investigations of the rhizosphere require high-resolution imaging techniques, which allow a look into the optically opaque soil compartment. We present the novel combination of magnetic resonance imaging (MRI) and neutron computed tomography (NCT) to achieve synergistic information such as…
-
Journal Article
Combining Visible−Near-Infrared and Pedotransfer Functions for Parameterization of Tile Drain Flow Simulations
Estimation of soil hydraulic parameters is essential when generating a hydrogeological model for simulating water flow dynamics in an agricultural field. However, estimation of the input parameters through direct measurements is time consuming and costly, and the spatial variability presents an…
-
Journal Article
Soil Hydraulic Properties Determined by Inverse Modeling of Drip Infiltrometer Experiments Extended with Pedotransfer Functions
A transient flow experiment using automated drip infiltrometers (ADIs) was performed on soil columns (about 6 dm) large enough to incorporate macropore flow effects. We investigated to what extent the estimated soil hydraulic parameters obtained from inverse modeling of these experiments are…
-
Journal Article
Water Table Impacts on Wastewater Storage around Onsite Drainfield Trenches: Evaluation by Model Simulation
Arkansas uses a unique system for determining effluent loading rates for onsite wastewater systems based on wastewater storage in unsaturated soil above a seasonal water table. Evaluation of the soil volume available for storage relies on estimates of the slope of the effluent plume away from the…
-
Journal Article
Bounds to Air-Flow Patterns during Cyclic Air Injection into Partially Saturated Soils Inferred from Extremum States
Soil-aeration procedures are widely used as an environmental practice for soil and groundwater remediation (removal of volatile compounds and enhancement of biological treatment) and less frequently as an agricultural practice to prevent root O deficiency. Analytical solutions to problems of air…
-
Journal Article
Probabilistic Inversion of Multiconfiguration Electromagnetic Induction Data Using Dimensionality Reduction Technique: A Numerical Study
Low-frequency loop–loop electromagnetic induction (EMI) offers several key advantages over many other geophysical techniques for proximal soil sensing. Yet, because of problems with the inversion of measured apparent electrical conductivity (EC) data, application of EMI for geophysical imaging and…
-
Journal Article
Can Drip Irrigation be Scheduled with Cosmic-Ray Neutron Sensing?
Irrigation is essential for maintaining food production in water-scarce regions. The irrigation need depends on the water content of the soil, which we measured with the novel technique of cosmic-ray neutron sensing (CRNS). The potential of the CRNS technique for drip irrigation scheduling was…